test: cover PersonTypeBadge, ExpandableText, PersonChipRow branches

PersonTypeBadge: one test per switch arm (INSTITUTION, GROUP, UNKNOWN)
plus the two no-render branches (unrecognised type, empty type).

ExpandableText: clamp detection, toggle visibility logic, expand →
collapse round-trip, default maxLines fallback.

PersonChipRow: sender-only, sender+arrow, abbreviated naming, max-two
visible receivers, +N overflow pill presence/absence, receivers-only
case (no sender → no arrow).

19 tests across three files. Each file uses afterEach(cleanup) and
queries via getByRole/getByText so tests stay decoupled from CSS.

Refs #496.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/shared/primitives/ExpandableText.svelte.test.ts

@@ -0,0 +1,57 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import ExpandableText from './ExpandableText.svelte';
+
+afterEach(cleanup);
+
+const longText = Array.from({ length: 60 }, (_, i) => `Zeile ${i + 1}.`).join('\n');
+const shortText = 'Zeile 1';
+
+describe('ExpandableText', () => {
+	it('renders the supplied text inside the clamped block', async () => {
+		render(ExpandableText, { props: { text: shortText, maxLines: 2 } });
+
+		await expect.element(page.getByText('Zeile 1')).toBeVisible();
+	});
+
+	it('does not show a toggle button when the content fits inside maxLines', async () => {
+		render(ExpandableText, { props: { text: shortText, maxLines: 100 } });
+
+		await expect
+			.element(page.getByRole('button', { name: /mehr anzeigen/i }))
+			.not.toBeInTheDocument();
+		await expect
+			.element(page.getByRole('button', { name: /weniger anzeigen/i }))
+			.not.toBeInTheDocument();
+	});
+
+	it('shows the "Mehr anzeigen" button when the content overflows the line clamp', async () => {
+		render(ExpandableText, { props: { text: longText, maxLines: 2 } });
+
+		await expect.element(page.getByRole('button', { name: /mehr anzeigen/i })).toBeVisible();
+	});
+
+	it('switches the toggle label to "Weniger anzeigen" after expanding', async () => {
+		render(ExpandableText, { props: { text: longText, maxLines: 2 } });
+
+		await page.getByRole('button', { name: /mehr anzeigen/i }).click();
+
+		await expect.element(page.getByRole('button', { name: /weniger anzeigen/i })).toBeVisible();
+	});
+
+	it('collapses again when the toggle is clicked while expanded', async () => {
+		render(ExpandableText, { props: { text: longText, maxLines: 2 } });
+
+		await page.getByRole('button', { name: /mehr anzeigen/i }).click();
+		await page.getByRole('button', { name: /weniger anzeigen/i }).click();
+
+		await expect.element(page.getByRole('button', { name: /mehr anzeigen/i })).toBeVisible();
+	});
+
+	it('uses the default maxLines (10) when the prop is omitted', async () => {
+		render(ExpandableText, { props: { text: shortText } });
+
+		await expect.element(page.getByText('Zeile 1')).toBeVisible();
+	});
+});